David Cameron holding a Q&A with workers at a warehouse during his fourth campaign visit to Newark. Photograph: ANDREW WINNING/REUTERS

5.46pm BST

Analysis - and five reasons why Ukip seem on course to come second in Newark

A kitchen sink - perhaps the one the Tories are throwing at Newark. Photograph: Dennis Galante/CORBIS

Will the Tory firewall hold? That was the question I asked this morning (see 8.15am)and the answer seems to be yes. I've only been here for nine hours, and it would be folly to claim to know for sure, but it does not feel as if the Conservatives are in much danger of losing. By this stage in a byelection experienced campaigners should know how the numbers are staking up, and I can't believe CCHQ would have let David Cameron anywhere near Newark this close to polling day if they thought a calamitous defeat was on the cards. The Ashcroft poll seems to bear this out. Roger Helmer, the Ukip candidate, was sitting at the table next to me in Starbucks a few minutes ago telling someone on the phone to ignore the Ashcroft poll because it did not allow for "differential turnout" (ie, Ukip voters being more motivated). Perhaps. But I would still be mightily surprised if he becomes an MP on Friday morning.

More interesting is the question of why the Tories are on course to win. Here are five reasons.

1. They have thrown the kitchen sink at this seat.David Cameron has been here four times, ministers have been ordered to come here at least three times and activists have been here in huge numbers. There were more than 500 people on the ground here at the weekend.

2. Ukip don't seem to be able to match the Conservatives for electoral expertise. The party has also been able to deploy hundreds of people on the ground (and their activists seem motivated by genuine enthusiasm, not official emails from Grant Shapps), but winning a byelection also requires backroom electoral flair and I'm not sure Ukip have acquired that yet. Their whole operation seems a bit more amateurish. And ...

3. Ukip have not identified a specific, local grievance. To win a byelection as an insurgent party, it helps to give voters the chance to punish the government for something specific. The Lib Dems in their prime were brilliant at this. But Ukip have not done that here. When I put this point to Ukip's campaign manager, Paul Oakden, he told me that the party was making the loss of A&E services at Newark hospital a key issue. Voters are bothered about that. But the decision has been taken, and it is not clear how voting for Roger Helmer would help.

4. Nigel Farage has taken a low profile. With Farage as the candidate, it might have been different. But he has only been here once. The party says he has been busy in the European parliament, where new groups are being formed after the election.

5. Ukip are perhaps a bit to polarising to be a really successful protest party. When I spoke to voters, I found some who were very hostile to Ukip. There is a definite anti-Ukip vote. The polling bears this out. Figures in this poll (pdf) show that people are more likely to say they will definitely not vote Ukip (52%) than Conservative (49%) or Labour (38%). Only the Lib Dems are more unpopular (56%). But that was not true in their byelection-winning heyday. Then the Lib Dems won because partly because people did not strongly object to them.

Obviously, if Ukip win on Thursday, I will have to revisit these theories. And the Kippers can have a good laugh at me. But you're entitled to know what I think, and that's my take.

In fairness, I should also point out that coming second would still count as a considerable result for a party that only had 4% of the vote here in 2010.

I'm heading home now. Thanks for the comments.

Updated at 5.51pm BST

5.07pm BST

I've spent much of the day in Newark town square. Ukip and the Tories have been very visible, but not Labour.

The Independent on Sunday understands that Labour, despite coming second in 2010, has all but written off its chances of winning in Newark, calculating that victory is so unlikely that it is not worth the estimated cost of £100,000 for leaflets and accommodation for party staff. While Labour is still fielding a candidate, Michael Payne, and there will be some shadow ministerial presence on the ground, the cash-strapped party is concentrating its scarce resources on the local and European elections and the general election battle next year. The move will effectively leave the way clear for Ukip's candidate, Roger Helmer, to gain ground on the Conservative, Robert Jenrik.

I asked Chris Bryant, who is running the Labour campaign, if this was true. As for not spending the full £100,000 allowed in a byelection (which the Conservatives and Ukip are doing), he was happy to 'fess up. "At any one time the Labour party has always got small resources and is trying to deploy them to best effect," he said. But he would not accept the party was not trying. It is knocking on a large number of doors, he said, and all the senior figures in the party have been here. Today there were six members of the shadow cabinet in the constituency: Harriet Harman; Ed Balls; Rachel Reeves; Tristram Hunt; Ivan Lewis: and Gloria De Piero.

4.56pm BST

My survey of opinion in Newark was less scientific than Lord Ashcroft's. He polled 1,000 people. I spoke to just over 20, in under an hour. But broadly my findings were in line with his. Of those who were willing to say how they would vote, 5 were Conservative, 3 Ukip and 3 Labour.

The numbers, though, don't matter. I was more interested in what people had to say. A few tentative themes emerged.

• The Conservatives are expected to win. Some people think Ukip will take the seat, but they were in a minority. Yet ...

• Ukip's anti-immigration stance does resonate very strongly with some voters. One former Conservative supporter was especially eager to tell me why he was going purple. "I'm unemployed," 43-year-old Andrew Shaw said. "I'm a qualified farmer. But every time I go for a job someone with a Polish accent beats me to it. I've got nothing against immigrants, but I think jobs should go to our own people.

• In so far as a local issue has dominated the campaign, it is the decision to downgrade what was a proper A&E unit at Newark hospital. But this is a decision that has been and gone, and it does not seem to be one that will sway the campaign.

• Not having any domestic policies is a serious handicap for Ukip. Several people mentioned this. "They have not told us any policies. I dread to think what they would do with the country," said Hilary Brock, a former care coordinator who is voting Conservative. Aubrey Gunn, a retired policeman sympathetic to Ukip, made a similar point. "I'm not sure that the have got the policies that will carry the country through," he said.

• But being anti-establishment does help Ukip. One man told me that he used to vote Conservative, but that he now felt that the "arrogance" of David Cameron and his colleagues was "unbelievable". When I asked what he meant, he replied: "Cameron's family is okay. He's got money in the bank. But I can't get proper care for my father."

• Robert Jenrick, the Conservative candidate, attracts mixed reviews. One person, who has met him, spoke very highly of him, and described him as a good local candidate. But another voter, attracted to Ukip because of their stance on Europe, said that he was concerned that Jenrick has not spoken out against Europe, and particularly discouraged by the fact that Jenrick is being endorsed by Ken Clarke. (See 2.22pm.)

The Conservatives are on course to hold onto Newark in the by-election on Thursday, according to a poll I have conducted in the constituency. I found the Tories on 42 per cent, with UKIP second on 27 per cent and Labour third on 20 per cent.

This represents a fall in vote share for all three established parties since the last general election: the Conservatives are down 12 points, Labour down two and the Liberal Democrats down 14 points on their 2010 score ...

This poll shows a bigger Tory lead than was found by Survation in their by-election poll published at the weekend. Interestingly, though, the two polls put UKIP within a point of each other. This would seem to suggest that the “spiral of silence adjustment”, used in my poll but not in Survation’s, made little difference in UKIP’s case. The adjustment works by re-allocating a proportion of those who refuse to state or claim they don’t know how they will vote to the party they voted for at the last election. It was introduced to help account for “shy” voters who were reluctant to admit their allegiance, a problem which had the effect of seriously skewing polls at previous elections. The similarity of the UKIP share in polls that did and did not use this adjustment suggests that there is nothing shy about the party’s voters; they do not coyly claim to be undecided.

Chris Bryant, the MP who is running the Labour campaign, has responded to David Cameron's comments about Robert Jenrick, the Conservative candidate, being the only candidate with a long-term commitment to the constituency. (See 1.27pm.)

Chris Bryant (@ChrisBryantMP)

@AndrewSparrow especially bizarre as jenrick has refused definitively to say he will move here

Mr Jenrick presents himself as a ‘father, local man, son of a secretary and small businessman and state primary school-educated’ candidate.

But that is not quite the whole story.

In fact, he and American wife Michal own not one, but two, £2 million homes in London and a £1 million country pile built by an 18th Century slave-trader.

Their Newark ‘home’ is a rented house obtained when he was picked as a candidate six months ago.

And his Party CV omits to say he went to a £13,000-a-year private secondary school.

Still, as a warm-up act for the prime minister, he was fine: articulate and on-message. He was selected as the Tory candidate towards the end of last year and, according to a member of his campaign team, he has conducted 250 meetings in the constituency since then. Looking at his election literature, it seems as if he's got a picture from almost all of them.

Three other things stand out from his leaflets.

First, he must be about the only Tory allowed by CCHQ to quote Kenneth Clarke approvingly. Clarke is MP for the neighbouring constituency, and a quote from Clarke endorsing Jenrick features prominently on at least one leaflet.

Second, Jenrick describes himself as someone who is "not a professional politician" but someone who would be a "strong, independent-minded voice" for the constituency. This is a jibe at Helmer, who has been an MEP since 1999. (As I said earlier, whether Jenrick would be "independent-minded" has yet to be established.)

And, third, Jenrick has drawn up a contract with voters which includes a promise to spend two weeks a year volunteering with local charities. I've got no objection to that at all, but it is interesting as an example of quite how much candidates have to do to get elected these days.

I'm now off to do some vox-popping in the market square. I will post again at around 4pm.

1.57pm BST

Did Cameron's Q&A win the Tories any votes? Not if the worker sitting in the row in front of me was anything to go by. "I'm voting Ukip," he said afterwards. "And even the foreigners working here are too."

1.27pm BST

Cameron's Q&A - Summary

Here are the main points from David Cameron's Q&A in Newark.

• Cameron said that, if Scotland left the United Kingdom, it would have to take its place behind countries like Macedonia and Serbia in the queue to join the EU. This is what he said when a Scottish worker at the distribution centre asked what would happen to Scotland's EU membership if it voted to leave the UK in the referendum.

The strictly factual answer is that if Scotland vote for independence, they are no longer members of the European Union and it has become clearer and clearer since this campaign started that they would have to reapply to join the European Union. And as such, as an independent country, they would. have to queue up as it were behind other countries, for instance those in the Western Balkans, that are already on the path towards membership.

• He suggested that people living outside Scotland should have had a vote in the independence referendum.

The franchise for this referendum was very much set by the Scottish parliament, and they decided to include Scottish people, all people living in Scotland, not Scots living in the rest of the United Kingdom. In many ways, that's a source of regret. But it is their decision.

• He confirmed that he was opposed to Jean-Claude Juncker, the former prime minister of Luxembourg, becoming the next president of the European commission. The EU was too big and bossy, he said. "We need peope who get it," he went on, clearly implying Juncker did not fully appreciate the need for EU reform.

• He played down suggestions that the government is hoping to restrict free movement of labour within the EU for existing member states.

• He confirmed that he wanted the minimum wage to rise to £7 an hour.

• He hinted that Britain might welcome the chance to bid again to host the 2022. In his opening remarks he talked about the inquiry into Qatar's bid and said: "We'll see what happens." But later, when asked if the 2022 bid should be re-run, he gave a more conventional answer.

There is an inquiry under way, quite rightly, into what happened in terms of the World Cup bid for 2022. I think we should let that inquiry take place rather than prejudge it.

My memories of that bidding process are, as I've said earlier, not happy ones in terms of the way the whole thing was arranged and the role of Fifa and the rest of it.

Let's let the inquiry take place.

• He played down suggestions that England might want to boycott the 2018 World Cup in Russia because of events in Ukraine.

As for the future of the World Cup in 2018, generally speaking we should try to keep sport and politics separated. I think we should use that as a rule. In extremis there are occasions - Zimbabwe, obviously South Africa - there are occasions where it is right to not take part in a sporting occasion but on the whole we should try and keep them separate.

• He confirmed that he wanted to continue cutting taxes.

We said we would cut taxes – now I would like to cut taxes more but we have from this year met the pledge that of saying you can earn £10,000 before you pay any income tax.

• He said that, although people might not like everything he did, they knew what his priority was as prime minister: Britain's economy.

You know what you get with me. You'll get even more of it if I get a majority ... You do know, with me as prime minister, you know what you get. You might not like all of it, I'm sure you don't. But you know what you get; it's about Britain's economic interests. Because in the end that is not some fancy term. That is about the stability and prosperity and peace of mind that all of you have, having a job, knowing the economy is on the right track.

• He said people should vote on Thursday, even if they did not vote for the Conservative candidate.

• He said the Conservative candidate, Robert Jenrick, was the only one with a long-term commitment to the constituency.

Remember all those posters years ago about a dog is for life, not just for Christmas. Well, it's a bit the same with your member of parliament. I know Robert will be here working hard because he's committed to the long-term future of people in Newark and Nottingham. The other parties just see this as trying to make a bit of progress for something else they want to do elsewhere in the country.

Now, back to the byelection contest.

David Cameron during his Q&A session at the Knowhow electrical goods warehouse in Newark. Photograph: ANDREW WINNING/REUTERS

Updated at 1.38pm BST

12.38pm BST

Here's a picture of David Cameron doing his Q&A in the Knowhow warehouse in Newark.

I'm sorry about the long radio silence earlier. But service should be a bit better this afternoon, because I'm now installed in the Starbucks in Newark town square, where my computer is speaking to the internet.

12.10pm BST

David Cameron's Q&A in Newark

Here is the summary of David Cameron's Q&A that I wrote up as it was going on. We were in a huge distribution warehouse, and the pictures probably looked impressive. But there was a downside; I could not connect to the internet.

Personally, I thought the most interesting line was Cameron's assertion that Scotland would go to the back of the queue for EU membership if it voted for independence, and that it would be behind applicant countries from the Balkans. But I will post a proper summary shortly.

Q: Why can't benefits be capped at the minimum wage? We come to work, but people on benefits are staying in bed having lots of children.

Cameron says this is what the government was doing. It had capped welfare. It would go on capping welfare, he said.

Q: Given the amount of people in Newark, are there any plans to increase the size of the hospital?

Cameron said he knew people were disappointed that services at the hospital were reduced under Labour. But the future of the hospital was safe, he said. Decisions are now taken locally. And the new NHS England chief executive, Simon Stevens, was only saying last week how much he supported community hospitals. That was one of the reasons Cameron was so keen on Stevens getting the job.

Q: What are you doing for young people?

Cameron says the key thing was to improve the economy, so jobs were available. But he said schools needed to get better at providing young people with information about alternatives to university.

Q: What will happen to Scotland's EU membership if they vote for independence?

Cameron said Scotland would cease being a member of the EU. It would have to queue up behind other countries to join, and it would be behind countries in the Balkans.

But he said he was confident the no vote would win.

Q: Do you think the World Cup bid should be re-run?

Cameron said an inquiry was underway. His memories of that bidding process were not happy ones, he said.

Q: Should we rethink competing in the 2018 World Cup in Russia?

Cameron said generally it was best to keep sport and politics seperate. There were exemptions – Zimbabwe, for example – but generally he did not want to merge them.

Q: In the FT in November you said you were just pushing for restrictions on EU migration from future member states. But now your colleagues are implying you want to restrict immigration from some current countries. What is your position?

Cameron says he wants a tougher migration system. There should be longer transitional controls on new members, he said. And he said free movement of labour should not be an unqualified right. It should not be a right to travel to another country to claim benefits.

Q: Are you wasting political capital trying to block Jean-Claude Juncker's appointment as the next president of the European Commission?

Cameron said he had a very clear view of the kind of EU he wanted. The EU was too big and too bossy, he said. And it was important to have people running the EU who get that, he said. That is his clear instruction on this. He said he looked forward to the debate continuing in Europe.

Q: Was it a mistake to close the A&E unit at Newark hospital?

Cameron said he did not want to go back over every decision in the past. But the system had changed, he said. The money was now spent by local clinicians.

Q: What can you do about people who want to stay on benefits and not work?

Cameron said you needed a stick and a carrot. The stick involves benefits offices having new powers to take benefits away from people who refuse jobs. Benefits offices now have those powers, he said. And the carrot involves helping people into work. It has set up the work programme, which is a programme helping people finding work.

Q: Are you campaigning here because you are worried about Ukip?

Cameron says in byelections, and in politics generally, you should never take anything for granted. He says he wants Robert Jenrick in parliament because he will support the government's economic plan.

Patrick Mercer let the people of Newark down, Cameron said. He said this was his fourth visit to the constituency, and he wanted to explain why people should vote for Jenrick.

Q: What size TV do you have at home?

Cameron said it was an old Thomson 28 inch. He was thinking the other day he needed a new one. And he knows where to go to get one, he said. (Knowhow distribute TVs.)

The questioner then told him about the Knowhow cashback offer. Cameron said he deserved to win the salesman of the month competition.

Q: What are you going to do to increase self employment in the UK?

Cameron said self-employment was increasing rapidly. Government programmes were available to help people set up their own firms, he said.

Q: What is the UK doing about Syria?

Cameron said it had been extremely difficult to address this problem. Humanitarian help from the UK was keeping people alive, he said. He said there was a legitimate opposition to President Assad. The UK was helping it, not with weapons, but with advice.

The British government was also trying to stop people from this coutry being radicalised by fighting in the civil war. This would be a topic that would come up at the G7 summit this week, he said.

Q: If you had to form a coalition after the next election, who would you prefer as partners: the Lib Dems, Unionists from Northern Ireland or Ukip?

Cameron said he would not answer that. People should let the Tories try to win outright, he said.

In 2010 he thought forming a coalition was the right thing to do, he said.

With me as prime minister, you know what you get, he said. His priority was economic stability.

He said he hoped people would vote on Thursday. He hoped they would vote for Robert Jenrick. But, above all, they should vote, he said.

Updated at 12.31pm BST

11.48am BST

David Cameron has just finished addressing staff at the Knowhow distribution warehouse in Newark. He did a Q&A, the internet coverage isn't great so haven't been able to cover it live but I'll post an update summary shortly.

Today, on his blog, he's published an angry response, threatening to sue. It takes the form of a letter to the Mail on Sunday's political editor, Simon Walters. Here's an extract.

A few days ago I took time out of my busy by-election schedule for an interview with you. You raised the issue of homosexuality. I was reluctant to spend time on it, as it is not high on my agenda and it certainly doesn’t seem to exercise voters in Newark — it has never once been raised with me in the street or on the doorstep. And I am becoming increasingly frustrated by the media’s relentless obsession with a few tangential remarks on social issues from years ago, and reluctance to address the real issues of either the euro-elections or the Newark campaign. Nevertheless I answered your questions clearly and honestly.

So I was shocked to read your subsequent story, in which you assert that I “called for gay cures on the NHS”. This is a deliberate and defamatory lie. I said no such thing. You have deliberately and knowingly published a false and defamatory statement a few days ahead of a critical by-election, with the prima facie objective of influencing the outcome of that election. I understand that this represents an offence under electoral law.

Nigel Farage, the Ukip leader, poses with Roger Helmer in front of a campaign poster for Helmer, the Ukip candidate in Newark. Photograph: Andrew Yates/AFP/Getty Images

• 10% of people who voted UKIP in the European elections last week told Survation they would vote Conservative in next week’s by-election, with 72% of these voters indicating they’ll stick with UKIP.

• One quarter of those who voted Conservative in 2010 in Newark are planning to vote UKIP in next week’s by-election. 44% of Conservative 2010 voters told Survation they were ‘considering’ voting UKIP next week

• Of those who did not vote in 2010, almost a third (31%) are planning to vote UKIP, while 18% are planning to vote Conservative.

8.33am BST

Here are three articles about the byelection I've found particularly helpful. They were all written by journalists who visited Newark last week.

I visited Newark today to find out how the battle is going. My overall impression is that the Ukip’s operation is being completely dwarfed by the Conservatives. Over 1,000 Tory activists were here last Saturday, with the same expected again this weekend. MPs and ministers are being continuously bussed in ....

In hindsight, Nigel Farage may regret his decision not to stand in Newark. His face appears on the local Ukip leaflets and Helmer has even admitted ‘Nigel has that enormous box office presence’. If Newark is a repeat of last year’s Eastleigh by-election — and Ukip just miss out on the seat — Farage will be kicking himself. If his party pull it out of the bag and win, it would be a game changer. Given the strong Conservative operation here, it seems they are also aware of the high stakes. But judging on what I’ve seen today, it’s likely Jenrick will roll home, albeit with a slimmer majority than his predecessor.

So who is going to win? I do not know and it would be foolish to predict. But what is clear is that the stakes are high. For the Tories, this is a chance to draw a line after some poor elections and claim that UKIP have reached their high water mark. For UKIP, it is a chance to reach that holy grail for any new party, a foothold in Westminster. For Labour, it is a chance to test its appeal in Middle England. And for the Lib Dems, it is simply another hurdle to get over before they can stop talking about Lord Oakeshott and try to move on.

The spirited, if slightly amateur, Ukip byelection operation suggests that the "People's Army" needs to brush up on logistics if it is to topple the Westminster political establishment. These flaws are not lost on theConservatives, who believe that the byelection, in which they are defending a majority of 16,152, will mark the moment when the Ukip bandwagon is slowed, if not entirely halted, as Britain's insurgent political force encounters the immense challenge of contesting Westminster seats.

8.15am BST

On Thursday voters in Newark, in Nottinghamshire, will choose a new MP in a byelection. Patrick Mercer, the Conservative MP who resigned after being caught in a cash-for-access scandal, had a 16,152 majority over Labour in 2010 and by rights the Conservatives ought to hold it easily. But polling takes place just two weeks after the European elections and Ukip are trying to build on their victory in the Euros by making Newark the place where they win their first seat in parliament.

The Conservatives are determined to stop them. They want to turn Newark into the firewall that blocks the relentless purple advance.

I'm currently on my way to Newark and I'll be blogging from there during the day, covering campaigning and background to the byelection. Because I will be on the move I won't be posting quite as regularly as I do when I write my normal blog. And today I will just be focusing on Newark.